The study, published in the Journal of Physiology: London, was carried out by Department of Psychology and the Department of Biology of Physical Activity at the University of Jyväskylä in Finland.

Lead researcher Professor Heikki Kainulainen said: "Aerobic exercise, such as running, has positive effects on brain structure and function, for example, the generation of neurons in the hippocampus, a brain structure important in learning.

"Aerobic exercise, such as running, has positive effects on brain structure and function"

Prof Heikki Kainulainen

"It has been unclear whether high-intensity interval training, referring to alternating short bouts of very intense anaerobic exercise with recovery periods, or anaerobic resistance training has similar effects on hippocampal neurogenesis in adulthood. "

The team studied rats who underwent sustained running, HIT and resistance training

Prof Kainulainen added: "The results indicate that the highest number of new hippocampal neurons was observed in rats that ran long distances and that also had a genetic predisposition to benefit from aerobic exercise.

"Compared to sedentary animals, HRT rats that ran voluntarily on a running wheel had 2-3 times more new hippocampal neurons at the end of the experiment.

"Compared to sedentary animals, HRT rats that ran voluntarily on a running wheel had 2-3 times more new hippocampal neurons at the end of the experiment"

Prof Heikki Kainulainen

"Resistance training had no such effect. Also the effects of HIT were minor. To conclude, only sustained aerobic exercise improved hippocampal neurogenesis in adult animals.

"It may be possible to increase the neuron reserve of the hippocampus and thus improve preconditions for learning by promoting neurogenesis via sustained aerobic exercise such as running."

The rats used had a genetically high response to aerobic training (HRT) and those with a low response to aerobic training (LRT).

The exercise training period was six to eight weeks running, HIT or resistance training during which control animals of the same rat strain remained in sedentary conditions in the home cage.

Prof Kainulainen added: "The result is important because, according to previous research, the new hippocampal neurons produced as a result of neurogenesis are needed among other things for learning temporally and spatially complex tasks.

"It is possible that by promoting neurogenesis via sustained aerobic exercise, the neuron reserve of the hippocampus can be increased and thus also the preconditions for learning improved also in humans."